Exercise could help reduce your risk of losing the ability to carry out basic functions of living as you age, a new study reports. And it could help head off disability even if you're overweight.

Researchers at Stanford University assessed the level of exercise and body mass indexes of 805 people aged 50 to 72 each year from 1989 through 2002. The study participants were categorized into four groups: overweight active; overweight and inactive; normal-weight active; and normal-weight inactive.

Those who exercised an hour or more a week were considered active and a body mass index of 25 or less was considered normal. The study participants were largely white (72 percent) men (96 percent).

After 13 years the overweight active men had significantly less disability than both overweight and normal-weight inactive groups. Normal weight active participants also fared better than both inactive groups.

The study, published in the current issue of the Journal of Public Health concluded that exercise decreased the likelihood of becoming disabled in this group of seniors and was largely independent whether the person was overweight or not.

The authors suggested that public health efforts to prevent senior citizens from experiencing functional decline should focus more on exercise instead of weight.